Adolescence is a health paradox;it is a time of peak health and strength, however it is also strongly associated with increased morbidity and mortality compared to the rest of the life span. Strong propensity toward taking risks is thought to be associated with high rates of accidents, psychopathology and mortality among adolescents. Inadequate sleep has emerged as a serious public health problem, affecting roughly 45% of American adolescents. Late bed times and early school start times are the norm. Several studies have examined the relationship between sleep and health in adolescence and have revealed a link between sleep deprivation and adverse consequences such as increased accidents, psychpathology and mortality. However, there is a dearth of research focused on identifying modifiable contributors to the risk taking that likely underpins these adverse consequences. The proposed research aims to empirically evaluate the hypothesis that sleep deprivation increases adolescent risk taking. In a within subjects experimental design, participants from three age groups (pre/early pubertal adolescents age 10-13, mid/late pubertal adolescents age 13-16 and adults age 30-60) will come in to the laboratory and undergo two experimental conditions over a two week period;a rested condition and a sleep deprived condition. Performance on a behavioral measure of risk taking (Balloon Analogue Risk Task;BART;Lejuez et al, 2002) will be examined after both the rested and sleep deprived conditions. Mid/late pubertal adolescents will be the main target of this research since this is the age group who are reporting the most daytime sleepiness (Carskadon et al, 2004) and the age group that is reported to be the most vulnerable to emotion and behavior problems (Dahl &Lewin, 2002). If risk taking propensity is indeed sensitive to sleep deprivation as hypothesized, the implications are far reaching as a higher propensity toward taking risks is associated with an increase in driving accidents, alcohol and drug use, and taking sexual risks. Without controlled studies of sleep deprivation and risky behaviors, scientists and public policy makers can only guess about these important issues. Such knowledge is critical for (a) providing an empirical basis for guiding public policy (e.g., school start times may need to be later), (b) providing an empirical basis for health campaigns (e.g., information to parents about how to encourage better sleep in their teens) and (c) providing an empirical basis for developing interventions for sleep and affective functioning difficulties among youth. This research will provide means of giving adolescents the chance to achieve their full potential for healthy and productive lives, and to ensure their independence, and well-being, so they can safely navigate the challenges of this phase of development.